Composite hose having a grounding wire enclosed in a sleeve and wrapped about the core tube of the hose

ABSTRACT

A composite hose adapted for conveying pressurized pulsating fluids is provided with a grounding wire secured to a protective sleeve helically wound about the core tube of the hose and adapted to slip as a unit relative to the core tube and surrounding fibrous reinforcing sheath as the hose expands radially in response to pulsating pressure.

United States Patent 1 Whittaker et al.

COMPOSITE HOSE HAVING A GROUNDING WIRE ENCLOSED TN A SLEEVE AND WRAPPEDABOUT THE CORE TUBE OF THE HOSE Inventors: Dewey E. Whittaker, Ravenna;

Charles D. Jenks, Kent, both of I Ohio Assignee: Samuel Moore & Company,

Mantua, Ohio Filed: June 5, 1972 Appl. No.: 259,661

11.8. CI. 174/47 Int. Cl. F161 11/12 Field of Search 174/47; 138/103;

[ Dec. 18, 1973 [56] References Cited UNITED STATES PATENTS 837,51212/1906 Seeley 174/47 3,543,803 12/1970 Chrow 174/47 X PrimaryExaminerLaramie E. Askin Attorney-Richard K. Stevens et a1.

[57] ABSTRACT A composite hose adapted for conveying pressurizedpulsating fluids is provided with a grounding wire secured to aprotective sleeve helically wound about the core tube of the hose andadapted to slip as a unit relative to the core tube and surroundingfibrous reinforcing sheath as the hose expands radially in response topulsating pressure.

12 Claims, 3 Drawing Figures COMPOSITE HOSE HAVING A GROUNDING WIREENCLOSED IN A SLEEVE AND WRAPPED ABOUT THE CORE TUBE OF THE HOSE Thisinvention relates generally to composite tubing and more particularly toa hose for transmitting fluids under pressure in a spraying apparatussuch as a paint spray.

Apparatus for spraying liquids such as paint is provided with a pump andhose assembly for transmitting liquid under pressure from a supply tankto a spray gun nozzle. An electrically conductive ground wire is usuallyincluded throughout the length of the hose to drain off any staticelectricity developed at the spray nozzle of the hose to preventsparking when it approaches a conductor such as a steel beam. A hosehaving a flexible polymeric core tube, a fibrous reinforcing layer woundabout the core tube and a protective sheath is used to convey the liquidat a pressure which is sufficiently high to produce a spray. The hosemust be capable of expanding radially under the pulsation of the pump inorder to act as an accumulator which attentuates the pulses so as tominimize pulsating at the nozzle and thereby produce a relatively smoothand uniform spray of liquid. On electric motor operated paint spraysystems, the accumulator action also retards the rate of pressure changeaffecting the motor controlling pressure switch, thereby reducing thenumber of stops and starts of the motor controlling the fluid pump.

It has been proposed heretofore to wind a ground wire about the coretube as one of the braids of the reinforcing layer. However, the wirefrequently broke under pressure and the abrasion of the braid by thewire sometimes resulted in bursting of the hose.

It is proposed in U.S. Pat. Nos. 3,445,583 and 3,543,803 to providecomposite tubing for transmission of liquids from a pulsating sourcewith a grounding wire helically wound about the core tube and enclosedwithin a rupture resistant sleeve. The composite tubing disclosed inU.S. Pat. No. 3,445,583 is provided with a grounding wire disposedbetween the core tube and braid. The grounding wire is secured to thecore tube by a binder tape which covers the wire and is adhesively boundalong opposed sides of the wire to the core tube. A protective tape maybe disposed loosely over the binder tape. The hose disclosed in U.S.Pat. No. 3,543,803 is provided with a grounding wire enclosed in asleeve formed from a supporting tape disposed between the wire and coretube, a binder tape which covers the wire and a protective tape over thebinder tape. The binder tape is not adhesively secured to the wire. Thesupporting tape and protective tape are coextensive in width and theiredges which extend beyond the edges of the binder tape are securedtogether to form an enclosing sleeve. The supporting tape is secured tothe core tube. The conductive element is disposed in movable relationwithin the sleeve to accomodate expansion of the tube. While thedisclosed hoses have been found to be adapted for successfullytransmitting paints under most conditions, it has been found that insome applications and particularly at higher pressures of say 3,000 psior more the ground wire sometimes ruptures and the fragments are notconfined suffisisntly to maintain continuity of the static dischar esystem.

It is therefore an object of this invention to provide an improvedcomposite hose having a static discharge wire. Another object of theinvention is to provide a composite hose for use with a paint sprayingapparatus or the like which is adapted for transmission of fluids atpressures of 3,000 psi or higher and has a static discharge wire whichis resistant to rupture even in hose which will withstand fluidpressures of 12,000 pounds per square inch or more. A further object ofthe invention is to provide a composite hose with a grounding wirecoextensive with the length of the hose and helically wound about thecore tube of the hose which is less likely to rupture upon radialexpansion of the hose and which is protected against loss of electricalcontinuity if a rupture occurs.

Other objects will become apparent from the following description withreference to the accompanying drawing wherein:

FIG. 1 is an elevation, partially cut-away and partially in section, ofone embodiment of the invention;

FIG. 2 is an enlarged cross-section taken along the line 22 of FIG. 1;and

FIG. 3 is an elevation of a length of core tubing having a protectedground wire helically wound thereabout as it appears prior to thewinding of the fibrous reinforcing layer about the core tube.

The foregoing objects and others are accomplished in accordance withthis invention, generally speaking, by providing a composite hose havinga synthetic resinous core tube, a fibrous reinforcing layer about thecore tube, a protective sheath about the fibrous layer and a groundingwire enclosed in a sleeve disposed between the core tube and fibrouslayer and helically wound about the core tube. The sleeve is formedabout substantially the entire length of wire by placing a pair ofplastic tapes in face-to-face relationship on opposite sides of the wireand adhesively or otherwise binding the edges of the tapes togetheralong each side of the wire. Preferably, that surface of each tape whichfaces the wire carries an adhesive so that both tapes are adhesivelybound to the wire as well as to each other along each side of the wire.The tape which is disposed between the wire and the core tube should beat least as wide as the tape disposed over the opposite side of the wireif the latter carries an adhesive to avoid sticking of the sleeve to thecore tube. The invention thus provides a composite hose having agrounding wire enclosed in a sleeve which is not adhesively bound toeither the core tube or reinforcing layer and has an external surfacewhich will slip over the surface of the core tube or over the surface ofthe reinforcing layer.

It has been found that a grounding wire secured against relativemovement within an enclosing sleeve so that the wire and sleeve slip asa unit in response to radial expansion of the hose is less likely torupture when the hose expands than is a wire bound to the core tube.Moreover, by binding the wire to the sleeve and preventing relativemovement between the wire and the surrounding walls of the sleeve,fragments of wire produced if there is a rupture are confined closelytogether in the area where the rupture occurs thereby maintainingcontinuity of the electrical circuit.

Referring now to FIG. 1 of the drawing, a composite hose 10 has a nyloncore tube 11, a fibrous nylon braid reinforcing layer 12 helically woundabout tube 1 l and a polyurethane sheath 13 about the braid l2.Interposed between tube 11 and braid 12 and helically wound about tube11 is a grounding wire 14 enclosed in a sleeve 15. Sleeve 15 may beformed by placing wire 14 between two Mylar tapes 16 and 17 each havingan adhesive coated surface facing the wire and then helically windingthe resulting sleeve 15 about core tube 11. Alternately, sleeve 15 maybe formed about wire 14 by helically winding a Mylar tape 16 about thecore tube 11 with an adhesive surface on the tape 16 exposed. Thesurface of tape 16 facing tube 11 is free from adhesive. A flat braidedcopper wire 14 may then be helically wound over the tape 16. A secondMylar tape 17 may then be helically wound over wire 14 with its adhesivecoated surface facing the wire 14. Tape 17 should not be any wider thantape 16 in order to insure that it does not become adhesively bound tothe core. During the winding operations, the wire 14 becomes securedbetween tapes 16 and 17 which are pressed together along each side ofwire 14 to seal their edges together. A braid 12 and sheath 13 may thenbe placed over the core tube and grounding wire by conventional means.

A composite hose with a grounding wire 14 is shown in an exaggeratedcross-section in FIG. 2 to illustrate that the sleeve 15 is not attachedto either the braid 12 or core tube 11 and is free to slip to relieveconcentrated stresses in a given area. The grouding wire 14 and sleeve15 may move relative to tube 11 and braid 12 in response to expansion ofthe hose due to pulsating pressure.

The core tube 11 may be formed from any material suitable fortransmission of fluids under pressure such as polyurethane, polyethyleneor nylon.

The reinforcing braid may be any suitable material such as Dacron, thepolyester fiber soldby Dupont, nylon or the like. The reinforcingmaterial may be wound about the core in one or more layers andpreferably one to four layers. The sheath may be extruded nylon,polyurethane, polyvinyl chloride, polyethylene or other suitableabrasion and solvent resistant covering material.

The two tapes used to make sleeve 15 may be the same or different.Although Mylar tapes are preferred, other flexible films such aspolyethylene, polyvinyl chloride or the like may be used. Mylar is apoly(ethylene) terephthalate polyester sold by Dupont. The adhesive onthe tape may be any suitable one such as a pressure sensitive resinbased adhesive.

The grounding wire is usually a plurality of wires braided or twistedtogether to form a flexible, thin conductor. The pitch distance of thehelically wound wire may vary with the diameter of the core tubeinsolong as it is so disposed that it will not materially reduce theflexibility of the composite hose. However, it is preferred that thepitch distance Y be relatively great as indicated in H6. 3 of thedrawing. For example, a distance Y between corresponding axially spacedpoints on the convolutions of about 4 to 16 times the diameter X isadvantageous.

As the hose provided by the inventioii expands radi ally in response topulsating of the liquid being pumped therethrough, the grounding wire 14and sleeve 15 must respond by also moving radially outwardly. Sinceslippage between the smooth surfaces of the sleeve and the core tube onone side and between the smooth surface of the sleeve and the fibrouslayer on the other side will permit minor adjustments of theposition ofthe envelope, thereby reducing stress concentrations as the hose bulges,there is a decreased tendency for the filaments of the wire to becomeembrittled and break from bending back and forth. Furthermore, since anadhesive layer faces the wire on each side, any fragments of wireproduced when the wire ultimately ruptures can move very little so theyremain sufficiently close together to maintain electrical continuity ofthe grounding wire.

The grounding wire and its surrounding sleeve may be used to advantagein hoses designed for use at any internal pressure but it isparticularly advantageous in hoses having a minimum burst strength of12,000 psi or more.

The following sample hoses were made and tested to illustrate theincreased resistance of the hose provided by this invention to loss ofcontinuity of the grounding wire:

Sample A. A composite hose having a core tube, braid reinforcement andprotective sheath and a helically wound grounding wire secured to thecore with a binder tape covered by a protective tape.

Sample B. A composite hose having a core tube, braid reinforcement andprotective sheath and a grounding wire helically wound about the coretube. A supporting tape was disposed between the wire and core tube andwas adhesively secured to the core tube. A binder tape of less widththan the supporting tape enclosed the wire but was not secured to it. Anouter protective tape coextensive in width with the support tape wasdisposed over the binder tape and secured along its edges throughout itslength to the supporting tape.

Sample C. A composite hose made in accordance with this invention had acore tube, braid reinforcement and protective sheath and a groundingwire adhesively secured inside a protective Mylar sleeve helically woundabout the core tube. The sleeve was not secured to either thereinforcing braid or the core tube.

Samples A, B and C were essentially the same except for the means usedto protect the grounding wire. The core tubes were nylon. The tapes of Aand B were Mylar and polyvinyl chloride. The tape of Sample C was Mylaronly. The braid was nylon. The sheaths were polyurethane. Eight hoses ofeach sample were tested by introducing fluid into the core under animpulse pressure of 4i00 psi. This was continued for loout 5 0 hourswith each hose e iTpandfii gTadilly and conTracting over 100,000 times.An electric current was passed through the grounding wire of each hosewhile it was flexing. it was found that after only 1.6 hours flexing,three of the eight Sample A hoses were conducting electricity onlyintermittently. All eight of the Sample B hoses conducted electricityonly intermittently after 0.3 hour while all eight of the Sample C hosesconducted the electrical current continuously after flexing over theentire test period.

Although the invention has been described in detail for the purpose ofillustration, it is to be understood that such detail is solely for thatpurpose and that variations can be made by those skilled in the artwithout departing from the spirit and scope of the invention except asit may be limited by the claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A composite hose adapted for conveying pressurized pulsating fluidscomprising a core tube, a fibrous reinforcing material about the coretube and a grounding wire enclosed in a sleeve helically wound about thecore tube and disposed between the core tube and fibrous material, saidwire and sleeve being substantially coextensive in length with the coretube, said sleeve having an external surface adjacent the core tube andadjacent the fibrous material which is slidable thereover and aninternal adhesive surface bound to the wire, whereby the said wire andits enclosing sleeve may slip as a unit relative to the fibrous materialand to the core in response to radial expansion of the hose.

2. The composite hose of claim 1 having a protective sheath about thefibrous material.

3. The composite hose of claim 2 wherein the core tube is nylon, thefibrous material is nylon, the sheath is polyurethane and the tapes arepoly(ethylene) terephthalate polyester.

4. The composite hose of claim 2 wherein the core tube is nylon, thefibrous material is nylon, the sheath is nylon and the tapes arepoly(ethylene) terephthalate polyester.

5. The composite hose of claim 2 wherein the core tube is nylon, thefibrous material is a polyester, the sheath is polyurethane and thetapes are poly(ethylene) terephthalate polyester.

6. The composite hose of claim 2 wherein the core tube is nylon, thefibrous material is polyester, the sheath is nylon and the tapes arepoly(ethylene) terephthalate polyester.

7. The composite hose of claim 1 wherein the distance between axiallyspaced points on adjacent convolutions of said wire is greater than themaximum transverse dimension of the core tube.

8. The composite hose of claim 7 wherein the said distance is from about4 to about 16 times the diameter of the hose.

9. The composite hose of claim 1 wherein the wire is a flat braid ofcopper wires.

l0.'The composite hose of claim 1 wherein the sleeve is composedessentially of two tapes, one disposed between the wireand core tube andthe other disposed between the wire and fibrous material, said tapeshaving their facing surfaces adhesively bound to the wire and togetheralong each side of the wire.

11. The composite hose of claim 6 wherein the tapes are a polyester.

12. The composite hose of claim 1 having one to four layers of fibrousmaterial.

1. A composite hose adapted for conveying pressurized pulsating fluidscomprising a core tube, a fibrous reinforcing material about the coretube and a grounding wire enclosed in a sleeve helically wound about thecore tube and disposed between the core tube and fibrous material, saidwire and sleeve being substantially coextensive in length with the coretube, said sleeve having an external surface adjacent the core tube andadjacent the fibrous material which is slidable thereover and aninternal adhesive surface bound to the wire, whereby the said wire andits enclosing sleeve may slip as a unit relative to the fibrous materialand to the core in response to radial expansion of the hose.
 2. Thecomposite hose of claim 1 having a protective sheath about the fibrousmaterial.
 3. The composite hose of claim 2 wherein the core tube isnylon, the fibrous material is nylon, the sheath is polyurethane and thetapes are poly(ethylene) terephthalate polyester.
 4. The composite hoseof claim 2 wherein the core tube is nylon, the fibrous material isnylon, the sheath is nylon and the tapes are poly(ethylene)terephthalate polyester.
 5. The composite hose of claim 2 wherein thecore tube is nylon, the fibrous material is a polyester, the sheath ispolyurethane and the tapes are poly(ethylene) terephthalate polyester.6. The composite hose of claim 2 wherein the core tube is nylon, thefibrous material is polyester, the sheath is nylon and the tapes arepoly(ethylene) terephthalate polyester.
 7. The composite hose of claim 1wherein the distance between axially spaced points on adjacentconvolutions of said wirE is greater than the maximum transversedimension of the core tube.
 8. The composite hose of claim 7 wherein thesaid distance is from about 4 to about 16 times the diameter of thehose.
 9. The composite hose of claim 1 wherein the wire is a flat braidof copper wires.
 10. The composite hose of claim 1 wherein the sleeve iscomposed essentially of two tapes, one disposed between the wire andcore tube and the other disposed between the wire and fibrous material,said tapes having their facing surfaces adhesively bound to the wire andtogether along each side of the wire.
 11. The composite hose of claim 6wherein the tapes are a polyester.
 12. The composite hose of claim 1having one to four layers of fibrous material.